The present disclosure relates to harvesting articulated (jointed) combines and more particularly to straw chopper assemblies that provide uniform distribution of chopped MOG or straw.
Over decades of development of grain harvesting combines, an area of performance for the machine that has often not kept up with the expectations of the customers, is the handling of the residue that exits the rear of the machine after the grain has been (mostly) removed. It typically is desired that the material be chopped into smaller pieces and distributed across the swath cut by the header on the front of the machine. If done properly, this greatly facilitates ensuing tillage and/or seeding operations.
In the last two decades, there are many compounding factors that have led to significantly higher expectations of the performance of the residue handling systems to meet chopping and spreading performance criteria, such as width of spread versus header width; uniformity of spread across the width of the header swath; and quality of chop defined by the “fineness” or length and uniformity of the chop. A list of the confounding situations that require attention to detail include the following:    1. Effective “no till” farming practices now require that the chopped residue be quite uniformly distributed onto the land nearly in the uniformity that existed before cutting.            a. “Swaths” of heavy and light concentration severely hamper no till operations and subsequent yield expectations, herbicide efficacy, and soil moisture conditions.            2. With more powerful harvesters and ever increasing widths of the grain header that collects the crop and gathers it into the harvester, the residue spreading system also is required to extend to greater distances away from the side of the harvester, which is difficult considering the light, fluffy nature of the material being spread.    3. Soil and water conversation practices and expectations are increasingly requiring that the residue uniformly cover the surface of the soil to prevent both rain and wind erosion.    4. High production cropping has taught farmers that yield expectations from soil thickly covered with residue or thinly covered with residue are vastly different, it being unacceptable to have repetitive strips in the field showing these differences, which leads to reduced profit potential.    5. Achieving economic gain by reducing soil compaction translates into reduction of tillage, which was historically used to deal with the residue.    6. Ever-increasing crop grain yields have for the most part increased proportionally to the amount of residue that has to be dealt with by the harvester and ensuing machines.    7. Modern crops have been naturally or genetically modified to remain alive and “green” while the grain is dry enough to harvest, causing the harvester and its residue systems to have to deal with ever tougher, harder, and increased quantities of cut vegetative matter.
With this understanding, we can appreciate that traditional methods will not satisfy current demands, even with residue management (straw choppers and straw/chaff spreaders) tools for combines that have been evolving in recent decades. It was typical to place spinning straw spreader disks at the rear of the combine and dump the residue on these disks to be spun out onto the ground, as best as it could be. The material could be as-delivered from the thresher or it could be material that passed through an internal straw chopper present in certain current models of combines (e.g., Case IH, CNH Industrial America LLC, rotary combines) and, thus, cut to a shorter length before the spreaders flung the material outwardly onto the ground. In both cases, the energy imparted to the material was not sufficient to allow the material to be flung a sufficient distance to cover a swath from a wide header.
Another traditional method of residue spreading was to mount a transverse chopper mechanism at the rear of the separator hood, and deliver whole residue to the inlet of the chopper housing for chopping by rotating flail knives, which in turn imparted significant energy to the material due to the high speed of rotation. This velocity energy, then, is used to fling the material rearwardly into a “tail board” configuration that had straight and/or curved blades that were used to deflect the material flow increasingly outwardly to try to effect a wide spread. For the material that was to fall directly behind or somewhat outside of the width of the combine separator, this was very effective. However, the material that had to be deflected a considerable distance by a deflector fin that set at some significant angle to the rearward direction of velocity, the act to hitting and reflecting off the fin tended to consume a lot of the energy, thereby killing the ability for it to be thrown a good distance to the side of the machine.
To answer this deficiency, Redecop in U.S. Pat. No. 5,482,508 teaches that the chopper blades can be altered so as to cause them to generate significant air velocity that can aid in carrying the chopped material against and around the curve of the longer bent fins that deflect material to the side of the machine. This method was largely effective at widening the spread swath to header widths common to the 1990's, typically less than 40 feet in width. But a huge negative to this technique was a near doubling of the horsepower required to drive the chopper, which severely degraded the performance of the combine. And, as headers surpassed the typical 30 to 35 foot width of the 1990's up to 40 to 50 feet in the 2010's, this method proved impractical due to power consumption, if not inadequate in spread width.
Subsequently, in U.S. Pat. No. 6,547,169 Matousek teaches that if spinning disks are oriented in a (near) vertical orientation at the rear of the separator and are further configured to accept material from the rotor discharge, the spinning disks are capable of throwing the material to the side of the machine with significant velocity and, thus, reach greater distances. The founding principal of this work was that one should throw without deflecting the material toward the furthest distance desired, letting deflected material fill the distances that are less far away from the machine.
Again in U.S. Pat. No. 6,616,528, Wolters and Matousek teach that the same principal can be applied to side-by-side vertically oriented chopper disks also located at the rear of the separation chamber. And still others have chosen to place the spinning horizontal straw spreader directly behind the straw chopper hood, directly in the flow of chopped material exiting the transverse straw chopper with the hope that the spinning spreaders could change the direction of the rearward flow and fling it outwardly from the side of the machine. This system has met with mixed results, and is mostly incapable of the wide spread required.
The present disclosure is an improved straw chopper and spreader system that spreads the chopped material to the header width distances required by modern farming systems.